The invention relates to a method and an apparatus for the continuous recovery of organic polymers from their solutions or emulsions, wherein such a solution or emulsion is injected into a liquid which is immiscible with the solution or emulsion, is heated above the boiling point of the respective azeotrope and is located in a vessel and wherein a vapour stream is supplied concentrically to the stream of solution or emulsion.
It is generally known that solutions of polymers in organic solvents can be worked up by introducing such solutions into a hot liquid, preferably into an aqueous liquid, the temperature of which lies above the boiling point of the organic water azeotrope and in which the polymer does not dissolve. The organic solvent distills over and the polymer is precipitated. It can then be separated, for example by filtration. This method fails with all polymers which have tacky properties in solution or in the solid state.
A method for obtaining polymonoolefins, polydiolefins or olefinic mixed polymers from their solutions in hydrocarbon is known (DE-AS No. 1 179 375 corresponding to FR-PS No. 1 302 028) in which these solutions are introduced in filament form by means of cooled nozzles into the base of a column filled with water at above 80.degree. C. and the fine polymers which have risen to the surface of the water and are divided into small pieces are separated, the method only operating if the diameter of the filament or of the nozzle, the working temperature, the consistency of the solution and the discharge rate of the filament from the nozzle are maintained exactly during operation of the apparatus. As this has proven difficult, disturbances can easily occur during operation.
In particular, lumps of solid polymer are easily formed during an interruption or decline in the quantity of solution supplied.
In addition, a method for the continuous recovery of organic polymers from their solutions or stable dispersions in organic solvents is described in DE-PS No. 1 570 094 (corresponding to U.S. Pat. Ser. No. 3,553,186) which is characterised in that such solutions or dispersions containing a liquid which is immiscible with them are converted into an unstable coarse dispersion in which the immiscible liquid is the continuous phase, this dispersion is introduced through a nozzle into the base of a container which contains a liquid which is also immiscible with the polymer solution or dispersion, the temperature of which is higher than the boiling temperature of the organic solvent, wherein the flow rate of the dispersion from the nozzle into the heated immiscible liquid and the vaporisation rate of the organic solvent are controlled by a vapour stream guided annularly around the nozzle.
This method does not ensure optimum precipitation, particularly in the case of tacky polymers, and the residual solvent content in the polymer is still too high.